Water distillation system

ABSTRACT

A water distillation system (10) includes a boiling chamber (11) and a condensation chamber (12). Water is fed via an inlet pipe (13) to a degassing chamber (15) where volatile gases are removed from the water. The water is evaporated in the boiling chamber (11) and vapour is, in turn, condensed in the condensing chamber (12). Distilled water is collected in a water storage tank (30) and is used, with a pump (28) and entrainment device (27), to provide a substantial vacuum within the system (10).

The present invention relates to water purification systems and, inparticular, to a water distillation system which is substantially moreefficient than known systems.

BACKGROUND ART

There are a variety of methods of purifying water, one of these methodsbeing distillation. One method of distilling water includes vaporisingthe liquid water under a vacuum and then condensing the water vapour,once again under vacuum so that the liquid water which has beencondensed does not include any impurities.

OBJECT OF THE INVENTION

It is an object of the present invention to provide a water distillationsystem which is substantially inexpensive to install, and is relativelyefficient.

DISCLOSURE OF THE INVENTION

According to one aspect of the present invention there is disclosed awater distillation system comprising:

a water evaporator, a water condenser and a water storage tank, whichevaporator, condenser and tank are connected in series so that waterpasses from the evaporator to the tank via the condenser;

a water inlet to deliver feed water to the evaporator;

a water outlet from said tank;

means to reduce pressure in said evaporator and condenser relative toatmosphere;

a refrigerant condenser in said water evaporator;

a refrigerant evaporator in said water condenser; a throttle meansthrough which refrigerant from said refrigerant condenser passes to saidrefrigerant evaporator;

are refrigerant compressor to pump refrigerant from said refrigerantcondenser to said refrigerant evaporator; and

a heat exchanger in said water tank through which the refrigerant passesto cool water located in said tank, said heat exchanger being positionedoperatively after said throttle means and before said compressorrelative to the direction of flow of the refrigerant.

BRIEF DESCRIPTION OF THE DRAWINGS

Some embodiments of the present invention will now be described withreference to the drawings in which:

FIG. 1 is a schematic diagram of a water distillation system of a firstembodiment;

FIG. 2 is a cutaway front view of the water distillation system of FIG.1 illustrating the layout of the system in a housing;

FIG. 3 is a left side view of the housing of FIG. 2, with side panelsremoved;

FIG. 4 is a rear view of the housing of FIG. 2; and

FIG. 5 is a schematic diagram of a water distillation system of a secondembodiment.

BEST MODE OF CARRYING OUT THE INVENTION

A water distillation system 10 of a preferred embodiment includes aboiling chamber or evaporator 11 and a condensation chamber 12. Water isfed via an inlet pipe 13 having a solenoid valve 14 to a degassingchamber 15 where volatile gases are removed from the water. Thedegassing chamber 15 and the boiling chamber 11 have a pair ofconnecting pipes 16 and 17. As the boiling chamber 11 and degassingchamber 15 are positioned at the same level, the water level 18 withinthe chambers 11 and 15 is the same and controlled by level switches 19and 20.

The boiling chamber 11 is connected by a vapour outlet pipe 21 to thecondensation chamber 12. The boiling chamber 11 also has a concentrateoutlet 22 which is opened and closed by a solenoid valve 23. Anothersolenoid valve 24 is attached to an air inlet 25 at the top of thedegassing chamber 15. The bottom of the condensation chamber 12 has anoutlet pipe 26 which is connected to an entrainment device 27 whichentrains the condensate therein. A pump 28 connected into a pipe 29 isused to circulate water in the pipe 29 to a cold water storage tank 30.The circulated water in the pipe 29 and tank 30, with pump 28, are thesole means required to achieve a vacuum of up to approximately 96% inthe outlet pipe 26 of the condensation chamber 12 which ensures that avacuum is maintained throughout the system 10 in the degassing chamber15, the boiling chamber 11, and the condensation chamber 12.

The energy required for the evaporation of water in the boiling chamber11 is supplied by a refrigeration system 31. The refrigeration system 31has a single refrigerant circuit and includes piping 39 which carriesR22 gas. A compressor 32 is used to force the R22 gas through therefrigeration system 31. The system 31 further includes a desuperheater33 a condensing coil 34 located below water level 18 in the boilingchamber 11, a capillary restrictor 35, or other suitable throttle means,a cooling coil 36 located in the cold water tank 30 and an evaporatorcoil 37 located within the condensation chamber 12.

The system 10 also includes as a preferred feature a hot water tank 40which is connected to the cold water storage tank 30 via a pipe 41having a non-return valve 42. The hot water tank 40 includes an electricheating element 43 to heat the water located therein.

The operation of the system 10 requires a vacuum of up to 96% beingachieved by circulating the water at a temperature of 4° C.-7° C. fromthe cold storage tank 30 through pipe 29 and the entrainment device 27by the pump 28. The water in the cold water storage tank 30 is cooled bythe refrigeration system 31.

The refrigeration system 31 is also used to evaporate the water in theboiling chamber 11 when it is passed through the condensing coil 34. Thehot R22 gases from the compressor 32 are first cooled to the requiredtemperature for evaporation by the desuperheater air cooler 33. Thetemperature of the water within the boiling chamber is controlled by athermostat 51 which controls the temperature of the R22 to be in therange 35° C.-55° C. The heat of the condensation of the R22 gas in thecondensing coil 34 provides the energy required for evaporation of thewater in the boiling chamber 11. The boiling temperature of the water issubstantially lower than the atmospheric boiling temperature of waterdue to the substantial vacuum in the system 10.

The water vapour passes through the vapour outlet pipe 21 and isreceived within the condensation chamber 12. The water in the coldstorage tank 30 is maintained in the temperature range of 4° C.-7° C. bypassing the R22 gases through the cooling coils 36 in the cold watertank 30. A thermostat 52 controls the temperature of the water withinthe tank 30. The evaporater coil 37 within the condensation chamber 22is used to condense the water vapour which in turn goes from thecondensation chamber 12 to the entrainment device 27.

For the water distillation, the feed water is fed to the degassingchamber 15 via the solenoid valve 14. Volatile gases are removed fromthe feed water at this stage. A level switch 53 controls the level ofthe water in the degassing chamber 15 and the boiling chamber 11.

The degassed water is then fed by gravity to the boiling chamber 11where it is heated to the desired boiling temperature and the resultingwater vapour is fed to the condensing chamber 12 via the vapour outletpipe 21. The water vapour which is condensed by the evaporater coil 37within the condensation chamber 12 is removed by the entrainment device27 and is pumped by the pump 28 to the cold water storage tank 30.Depending on the quality of the feed water, when the concentration ofthe contaminants in the boiling chamber 11 reaches a certainpredetermined level, solenoid valves 23 and 24 are automaticallyoperated to let the concentrate flow out by gravity to a blown down tank63 (FIGS. 2-4).

Level switches 54 and 55 within the cold water storage tank 30 are usedto control the level of the water in this tank. When the level of thewater in the tank reaches the level switch 54, the pump 28 stopsoperating until the level of the water drops below level switch 55. Whenthe tank 30 is full and the pump 28 has stopped, pure water will stillbe produced and stored in the condensation chamber 12. This is due tothe fact that the vacuum once establishes nearly self-generated by thecondensation of the water vapour. The production of pure water willcontinue until the evaporator coils 37 are completely submerged in thewater.

During the period that the pump 28 has stopped, the thermostat 51controls the operation of the compressor 32 to keep the watertemperature in the tank 30 at a predetermined value.

During this cycle the purified water in the cold water tank is able tobe removed as required from an outlet 61 and is also able to be fedthrough the non-return valve 42 to the hot water tank 40 where the wateris heated by the heating element 43 which is controlled by a thermostat44. Hot water is available through outlet 62. Therefore hot and coldwater is possible in the water distillation system 10.

Illustrated in FIGS. 2-4 the system 10 is located within a housing 64.The water inlet 13 is supplied from a supply storage tank 65 which hasan inlet 66 and an overflow outlet 67. All the components are located inthe housing 64 which has a cooling fan 68 and a blowdown outlet 69. Acontrol unit 70 houses the power and control circuit which are used tocontrol and operate the system 10.

The water distillation system 80 of a second embodiment as illustratedin FIG. 5 includes a boiling chamber 81 and a storage tank 82. Tap wateris fed to the boiling chamber 81 via a solenoid valve 83 and a degassingchamber 84 where dissolved gases are flashed out of the water which isfed, in turn, to the boiling chamber 81. The degassing chamber 84 alsoacts as a level controller of the boiling chamber 81, as these twochambers 81 and 84 are on the same level and therefore the level of thewater within the two chambers 81 and 84 is identical as two pipe 85 and86 join the two chambers 81 and 84. A level switch 87 is used to controlthe solenoid valve 83 and hence the introduction of water into thedegassing chamber 84 and hence the water level 88 in the boiling chamber81.

The boiling chamber 81 which is therefore partially filled with water,has an electric heating element 89 which heats the liquid water. A levelswitch 106 is used to ensure water level does not go lower than acertain level. An entrainment separator 90 above the water level 88 isused to entrain the water vapour as the water evaporates.

The storage tank 82 includes an entrainment device 91 which is connectedby piping 92 to a pump 93. The other side of the entrainment device 91is connected to pipes 94 which connect to the boiling chamber 81. Motherpipe 107 is connected in parallel to the degassing chamber 84 toequalise pressure within the system 80. The pump 93 in conjunction withthe entrainment device 91 pipes 94 and 107 located between the storagetank 82 and boiling chamber 91 and the degassing chamber 84, as well asthe boiling chamber 91 and the degassing chamber 84.

An air condenser 95 preferably made of stainless steel, has an uppersection 96 and a lower section 97 which is used to condense the watervapour in the pipes 94 as well as dissipating heat generated by the pump8. A fan 98 is used to blow air over coils 94 and 100 respectively toeffect the condensation and cooling.

In operation, tap water is fed through the solenoid valve 83 to thedegassing chamber 84 where dissolved gases are flashed out before wateris fed, in turn, to the boiling chamber 81. The vacuum generated by theentrainment device 91 and pump 93 (a vacuum of approximately 92%) in theboiling chamber allows the liquid water to boil in the temperature range40° C.-45° C. The water vapour passes through the entrainment separator90 before being fed to the condenser 95 through the pipe 94. The watervapour is condensed and cooled within the air condenser 7 and the pureliquid water is which is produced is then sucked by the pump into theentrainment device 91. The pipe 107 is used to equalise pressure. Thewater is then cooled by the lower section 97 of the air condenser 95 andreturned to the storage tank 82 where it is able to be entrained by theentrainment device 91. The storage tank 82 has two level switches 101and 102 and when the level in the storage tank 82 reaches the levelswitch 102, the system 80 is turned off and a solenoid valve 103 in theboiling chamber 81 opens to let the concentrate in this chamber 81 to beremoved via a blowdown outlet 104.

The distilled water in the storage tank 82 is then used as required. Thewater is removed by the pump out solenoid valve 105. When the level inthe storage tank reaches the level switch 101, the system recommences toproduce enough distilled water as required.

The system can be used continuously to provide distilled water or can beused in discrete amounts.

The system 10 of the first embodiment is useful in that any volatilegases in the feed water are separated under vacuum, in the degassingchamber 15, remain separated until the exit of entrainment device 27.This is due to the fact that because the volatile gases are under a highvacuum, they have no affinity to be dissolved back into the distillatein the pipe 29, even though the volatile gases and distillate are incontact, at nearly atmospheric pressure for a short period of time, ieapproximately less than one second, only a minute amount of volatilegases can dissolve back into the water. In addition, chlorine which isdissolved in the feed water, when separated in the degassing chamber 15acts as an antiseptic agent to cleanse the system 10.

The system 10 is relatively energy efficient, during the productioncycle, as the compressor 32 is used to evaporate the feed water in theboiling chamber 11, condense the vapour in the condensation chamber 12and maintain the water in the cold water storage tank 30 at atemperature in the range 4° C.-7° C.

During the cooling cycle, ie when the cold water storage tank 30 and thehot water tank 40 are full, and the pump 28 has been switched off, thedistillate (water) is stored in the condensation chamber 12 and thesystem 10 self adjusts the production rate with the available surface ofthe coil 37 and the level of the vacuum. Once the condensation chamber12 is full of water, the desuperheater 33 acts as a condenser while thecold water storage tank cooling coil 36 acts as an evaporator.

The arrangement of the system 10 allows the pump 28 and entrainmentdevice 27 to operate at 4° C. and produce a very high vacuum of up to98%, and the pump 28 has the additional feature of transferring thedistilled water to the storage tanks 30 and 40.

Boiling the water in the temperature range 35° C.-55° C. ensures thatthe vapour thus formed will not carry bacteria, mineral contaminants,dissolved solids including radioactive contaminants, through to thecondensing system of both embodiments.

Typical water quality resulting from city water feeds is approximately 1ppm of dissolved solids.

The foregoing describes only one embodiment of the present invention andmodifications obvious to those skilled in the art, can be made theretowithout departing from the scope of the present invention.

For example, the evaporation and condensation of the feed water andwater vapour, respectively, can be achieved by other means of heatexchange such as heating elements or cooling elements.

I claim:
 1. A water distillation system comprising:a water evaporator, awater condenser and a water storage tank, the evaporator, condenser andtank being connected in series so that water passes from the evaporatorto the tank via the condenser; a water inlet to deliver feed water tothe evaporator; a water outlet from said tank; degassing meansinterposed between said water inlet and said evaporator for removingdissolved gasses in said feed water and for maintaining a predeterminedlevel of said feed water in said evaporator; means for reducing pressurein said evaporator and condenser relative to atmospheric pressure,wherein said means for reducing pressure includes an entrainment deviceand a circulation pump to pump water from said water storage tank arounda circulation pipe, and wherein said pump receives water from said waterstorage tank and outputs water to a through input of said entrainmentdevice, a through output of said entrainment device returning water tosaid water storage tank, said entrainment device further including atransverse port interconnected to an outlet of said condenser toentrain, under vacuum, condensate from said condenser to water passingto said water storage tank; and a single refrigerant circuit, saidrefrigerant circuit including: a refrigerant condenser in said waterevaporator; a refrigerant evaporator in said water condenser; a throttledevice through which refrigerant from said refrigerant condenser passesto said refrigerant evaporator; a refrigerant compressor to circulatesaid refrigerant around said circuit; desuperheater means, through whichthe refrigerant passes, to cool the refrigerant, said desuperheatermeans being positioned operatively after said compressor and before saidrefrigerant condenser; and a heat exchanger, through which therefrigerant passes, located in said water storage tank to cool waterlocated in said tank, said heat exchanger being positioned in saidcircuit after said throttle means and before said compressor relative tothe direction of flow of the refrigerant about said circuit.
 2. Thewater distillation system as claimed in claim 1, wherein the water inlethas a control valve means to regulate feed water entering through saidinlet.
 3. The water distillation system as claimed in claim 2, whereinsaid evaporator has an outlet control valve which is able to be operatedto remove the water and any contaminants therein from said evaporator.4. The water distillation system as claimed in claim 3, wherein saidsystem includes a hot water storage tank which receives water from saidwater storage tank, said hot water storage tank having a heater element.5. The water distillation system as claimed in claim 4, wherein anon-return valve is positioned between said storage tank and said hotwater storage tank.
 6. The water distillation system as claimed in claim1 wherein said evaporator is maintained within the temperature range 35°C.-55° C. during operation of said system.
 7. The water distillationsystem as claimed in claim 1, wherein said water in said storage tank ismaintained within the temperature range 4° C.-7° C. during operation ofsaid system.
 8. The water distillation system as claimed in claim 1wherein said means for reducing pressure is a sole means for reducingpressure.